Analysis of cladding-mode couplings for a lensed fiber integrated with a long-period fiber grating by use of the beam-propagation method

Abstract

The beam-propagation method (BPM) is employed to analyze the coupling behavior of our scheme proposed previously, which combines a lensed fiber and a long-period fiber grating (LPFG) [Chen and Wang, Appl. Opt. 39,4490-4500 (2000)]. The influences of a core within the fiber lens are investigated. As for the fiber dependence of our coupling scheme, two typical fibers are studied: dispersion-shifted and single-mode, step-index fibers. With the BPM, the optimal coupling efficiencies for various source waists with corresponding lens radii and working distances are determined. We also compare the results with those obtained by use of the ABCD method and found that the BPM gives better agreement with experimental results.

Conversion and focusing of optical fiber modes with superimposed long period gratings

“…1(a). This conversion is necessary for efficient alignment and coupling between a laser source and an optical fiber and, also, between two fibers [5][6][7][8][9]. After entering the fiber, the beam is distributed among the fiber modes.…”

“…The complex-( , ) j e x y κ 12 [5][6][7][8] assumed that the input beam is predominantly transfered into a single cladding mode (CM). For this reason, in [5][6][7][8], conventional single LPG theory [2] was applied. Ref [9] suggested a converter consisting of superimposed LPGs that couple a number of CMs and the FM.…”

“…The beam is composed by optimization of the amplitudes and phases of the first five LP 0j modes generated from the input FM. The single LPG versions of such devices have been experimentally demonstrated previously [4][5][6][7][8]. The advantage of superimposed LPGs is that they possess much broader functionality and, at the same time, can be fabricated using the standard fiber grating fabrication technology [1,3].…”

Nanomaterial-based robust oxygen sensor

“…The same boundary conditions allow 100% coupling of the cladding bound modes of the luminescence signal back to the core. [1][2][3] We have utilized ruthenium complexes as oxygen indicators. These complexes have been well characterized for their use as an oxygen sensor.…”